DSS vs Siril vs ASTAP

Questions and answers about processing in StarTools and how to accomplish certain tasks.
Posts: 48
Joined: Thu Jul 30, 2020 5:06 pm

Re: DSS vs Siril vs ASTAP

Post by Carles »

bobharmony wrote: Sun Mar 28, 2021 6:15 pm Carles

I have just begun working with Siril as an alternative to DSS this past week, and am also liking what I am seeing so far. It seems that the stack produced by Siril shows a bit more detail than the DSS result. My particular interest is in Siril's capacity to apply background extraction from individual subs before stacking, as I image in a very light-polluted area and gradients are complex and fierce after stacking in DSS. Early results are promising but there is more testing to follow. I will be watching this thread with interest.

Hi Bob!

Yes I'm quite intrigued so far about the differences.
I stack using the scrip " OSC_Preprocessing"
this is what comes out when stacking
"Integration of 206 images:
15:26:36: Pixel combination ......... average
15:26:36: Normalization ............. additive + scaling
15:26:36: Pixel rejection ........... Winsorized sigma clipping
15:26:36: Rejection parameters ...... low=3.000 high=3.000
15:26:37: Background noise value (channel: #0): 1.181 (1.803e-05)
15:26:37: Background noise value (channel: #1): 1.103 (1.684e-05)
15:26:37: Background noise value (channel: #2): 1.180 (1.800e-05)
15:26:37: Saving FITS: file ../result.fit, 3 layer(s), 6080x4048 pixels"

So it seems it does Normalization, which I don't know to what point is good or not. I think to remember usually not recommended for StarTools but I don't know.
Haven't tested manual stacking parameters , so far only the default script and it looks pretty good to me...

What I don't like much is that it makes quite a lot of "mess" with files, not a mess as in disorganized but rather the amount of storage used!!

I've stacked 206 images, using 33 darks 30 dark flats and 2 master flats (haven't got the original flats since this is from few months back and I'm using different Gain/Offset so didn't see a point on keeping them.

Point is; I've used Drizzle processing this time and the "Process " folder has 82 Gb!!! worth of files! The final file , usually called "Target" <--- FYI, after stacking better change the name or make a copy, as it will overwritte it next stack.. <-- that is using the script, if you do manual I guess you can just select a file name.

So it makes a lot of in termediate files.. even more than ASTAP I think. But this time since it was drizzle, each file was resized so from the original 12mb , each file drizzled is 288mb. Might be a problem depending on the available disk space. But you can always keep emptying this folder after the stack.

I am stacking other old files, and they look better so far as well.

Will keep testing! ^^
If you guys do too, let me know what are the results and or settings used : )


Posts: 48
Joined: Thu Jul 30, 2020 5:06 pm

Re: DSS vs Siril vs ASTAP

Post by Carles »

Stefan B wrote: Sun Mar 28, 2021 7:42 pm Hi everybody,

with my last image I had some problems with the stack generated by DSS. Because of the 80% moon it was difficult for me to seperate the outer parts of M106 from the noisy background. After seeing the processed DSS stack the first conclusion was that it's just stupid to image broadband during a bright moon. But with this thread in mind I had a try with ASTAP and got a much better result.

Hi Stefan!

That's an awesome result with full moon!! I was shooting M101 yesterday too to stack with some days back data, and but haven't done it yet since tonight seems to be clear too and want to add some more :D
And your result encourages me to capture during the moon too! Still, M101 and M106 are "far" from the moon so guess it can be done more safely than, for instance, galaxies in Leo hehe but well, will see!!

Give it a go at Siril too, it is a lot faster than ASTAP! See if the result is any good for you :D But for now, that ASTAP result looks great! ^^

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